Electrical device



Sept. 18, 1928. 1,684,461

H. R. VAN DEVENTER ELECTRICAL DEVICE Filed Dec. 1. 1922 \nuen for B H.R Van Devenier Patented Sept. 18, 1 928.

UNITED- STATES 1,684,461 PATENT OFFICE.

HARRY R. VAN DEVENTER, OF NEW YORK, N. Y., ASSIGNOR TO DUBILIER CON- DENSER CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWABE.

ELECTRICAL DEVICE.

Application filed December My invention relates to an electrical device which may be used for a number of purposes. For the sake of illustration, I will describe the same as applied to a variable electrostatic condenser adapted for use in radio, telephone, telegraph and other electrical apparatus.

One of the objects of my invention is to rovide an electrical device in which rub- 10 ng, scraping or friction of the parts is eliminated.

Another object is toprovide an electrical device in which electrostatic capacity or impedance may be varied by infinitesimal steps.

Other objects will hereinafter more fully appear. I

In one embodiment, I have applied my invention to a variable condenser as illustrated in the accompanying drawing, in which Fig.

1 is a View in perspective of a variable condenser constructed in accordance with theprinciples of my invention.

Fig. 2 and Fig. 3 are modifications of Fig. 1.

Like figures of reference denote like parts wherever they are shown.

Referring to the drawing, the device here shown comprises a support or base 1, carrying a fixed conductive layer or member 2 which forms one plate or armature element of a condenser.

This fixed element may comprise any suitable material having suflicient conductivity to serve as an armature or electrode of a condenser. It may be secured to the base 1 in any desired manner, such as by the use of an adhesive between the element and base, or by screws, rivets, studs or other Well-known means.

The member 2 is clamped at one end under the binding post 8, the conducting surface of 2 being in electrical connection therewith. Theother end of 2 is insulated and spaced from the conductive member 3 which forms a plate or armature of opposite polarity.

()vcrlying the plate 2 is a suitable layer of insulation, such as a sheet of mica 15, which is glued or otherwise fastened to the element 2 in such manner as to serve as a dielectric in combination with elements 2 and 3.

Clamped under the binding post 7 and in electrical connection therewith is the conducting member 3prcferal' ly a spring, the outer end of which is bifurcated and engages 1, 1922. Serial No.- 604,395.

the grooved nut 5. This grooved nut 5 is internally threaded and is engaged b the threaded shaft 4, which passes 'reely through the collar 11, entering a tapped hole in the knob or handle 6.

The collar 11 is secured to the handle 6, but turns freely in the plate 1. The tapped hole in 6 is long enough to permit the shaft 4 to enter 6 for a sufiicient distance to operate the device as hereinafter described.

Figure 2 is a modification of the device in which the base member has an upwardly projecting portion 10 provided with a curved conductive surface.

Figure 3 shows in section a detail of a different arrangement of the binding posts.

In operation, referring to the form of device shown in Fig. 1 (the same being con nected in the circuit for which it is intended, the connections being made to binding posts 7 and 8) by turning the knob or handle 6, the member 3 will be gradually draWndown on the surface of the insulating member 15.

The member 3 may be of bronze or some other good conducting material, and as it gradually lies down upon 15, the electrostatic capacity between members 2 and 3 is gradually increased by reason of the increased effective area 1 provided by the decreased distance.

This drawing or lying down action will begin at the point 13 and progress toward the ri ht of the member 15 until the lower side of the member 3 is in contact with the extreme right hand end of the strip 15 such as at the po nt 14. It will be observed that the capacity between the members 2 and 3 may be varied by very small steps, (in fact, imperceptibly) from a maximum toa minimum by operating theknob or handle 6 to draw the strip 3 gradually into contact with 15, whereby the under surface of 3 is caused to gradually overlay the upper surface of 15 by touch contact. 1

By touch contact, I mean that the mem- 100 here 2 and 15 are caused to approach and recede from each other along a forwardly progressing line substantial] perpendicular to the opposed surfaces t ereof, thereby eliminating the difiiculties heretofore met in 105 devices of this character wherein a movable member, the equivalent of 3, is brought into engagement with a dielectric member, the equivalent of 15, by'means of a rubbing or sliding contact or the like. Such rubbing 110 knob or handle 6.

The modification shown in Fig. 2 consists in roviding the fixed conductive member 2 wit an upper curved or otherwise formed surface and in causing an insulating layer 15 to conform to such surface. The operation ofthis device is substantially the same as the device shown in the preceeding figures.

Figure 3 shows in section a modification in which both terminals 7 and 8 are located at the same end of the base 1, the terminals being adapted for front connection. A lat- 'eral extension of the conducting strip 2, as

shown in the other modifications, for connecting with a binding post is not required. Obviously the binding post or terminal '8 may be located at any desired place along the strip 2.

The simple construction of my device enables variable electrostatic condensers to be easily and cheaply constructed, particularly those of small capacity, such as .001 mf. or less, commonly employed in connection with radio telephone and telegraph circuits.

The objections heretofore met with in condensers having movable plates are eliminated by my invention for such condensers heretofore known have required accurate .and therefore expensive workmanship to prevent the movable plates from touching the fixed plates; or where a movable plate revolving between fixed plates covered with mica is employed and the movable plate has a rubbing contact with the mica, mica dust is created and gets between the movable and fixed plates and causes serious variations in the setting of the condenser.

lVhile I have shown and described but a single embodiment of my invention in the various modifications, I do not wish to be limited thereto since various other modifications, both in the circuit arrangement and in the structural features, may be made without departing from the spirit and scope of my invention, as set forth in the appended claims.

I claim as my invention:

1. A'variable condenser comprising a base, an element of electrically conductive material mounted on said base, a resilient element a bifurcated end to engage the grooved nut,

so that upon turning the shaft, the grooved nut can move the resilient element into close relation to the first-named element progressively throughout its length.

2. A variable condenser comprising a base, an element of electrically conductive material mounted'on the base, the base having a curved surface against which said element is disposed, a resilient movable element of electrically conductive material associated with thefirst-named element and arranged to be separated therefrom by a dielectric, said elements being maintained in proximity at one point and diverging from each other away from said point, a threaded shaft extending through the base and a grooved nut upon said shaft, the movable element having a bifurcated end to enable it to be stressed by the grooved nut when the shaft is turned, and moved into relatively close relation to the first-named elemen progressively throughout its length.

3. A variable condenser comprising a support, an element of electrically conductive material on said support, the support having a curved surface against which said element is disposed, a resilient movable element of conductive material associated with the said first-named element but separated therefrom by a dielectric, said elements being secured in close proximity to each other at one point, the movable element diverging from the first named element adjacent said point to the end of said resilient element, and means comprising a threaded shaft and a member controlled by said shaft and engaging the. divergent end of the resilient element for stressing said resilient element to move it into relatively close relation to the first named element progressively throughout its length.

In testimony whereof, I have hereunto subscribed my name this 29th day of November, 1922.

HARRY R. VAN DEVENTER. 

